1. Technical Field
The embodiments described herein relate to an optical system and, more particularly, to a contact type plasmonic nanometer grade (hereinafter, nano) optical probe, a parallel probe constituted of the same, a plasmonic optical apparatus including the parallel probe, and a method of fabricating the parallel probe.
2. Related Arts
Resolutions of optical systems used in a process of fabricating circuits must be enhanced to increase an integration density of a semiconductor integrated circuit. That is, circuit patterns with a fine line width are demanded to increase an integration density of a semiconductor integrated circuit and these circuit patterns depend on resolution of an optical system.
Accordingly, light sources and optical systems having the resolution below a wave length of an exposure light which has been using currently are required. However, to develop a new light source or to embody a new high-tech optical system requires high development expense and it is difficult to fulfill it in practice.
Therefore, studies on various methods of improving the resolution by alternating a current light source and a current exposure apparatus have been progressed. As one of the various methods, a method of fabricating fine patterns by a plasmonic effect based on a near-field is disclosed in Korean patent laid open No. 10-2005-0001086 by this applicant.
As disclosed in “A nano aperture with 1000× power throughput enhancement for VSAL system”, 2003, SPIE, Vol. 4342, pp 320-327, the plasmonic effect is a phenomenon that transmittance of the light passed through the hole of nm diameter disposed in a metal film is remarkably increased. If the Plasmonic effect is applied to a lithographic principle, transmittance and optical flux of an incident light are largely enhanced by the Plasmonic effect based on the near-field, so that fine patterns can be accurately fabricated.
It is very important to improve exposure uniformity in the lithography method using the near-field. The exposure uniformity depends on maintaining a distance between an optical structure which including a hole of nm diameter and a film to be exposed (this is, a photoresist film). That is, the distance is a basic structure for generating the near-field and the distance between the light source and the film to be exposed must be maintained below several ten nm. In addition, a parallel process technique which disposes probes having nano apertures in an array type is a method obtaining high productivity. However, it is difficult to control a gap between each of probes and a piece below several ten nm so as to near-field pattern several thousand or several hundred thousand parallel probes in practice.
In recent years, a method of maintaining the distance by interposing an immersion material layer or a wall is disclosed in “Micro-optical Two-Dimensional Device for the Optical Memory Head of an Ultrahigh Data Transfer Rate And Density System Using a Vertical Cavity Surface Emitting Laser Array”, Jpn. J. Appl. Phys. Vol. 41 (2002) pp. 4835-4840. However, the method can not ensure to uniformly maintain the distance between each of all probes disposed in parallel and a film to be exposed.